In prior art die casting machines having a frame comprised of left hand side and right hand side platens, the platens are supported by four parallel tie bars connected between opposed corners of the left hand side and right hand side platens. A moving platen having a die on one surface thereof is mounted on said tie bars for movement towards and away from an opposing die on the face of one of the fixed platens.
The use of four tie bars between the right and left hand side platens leaves less than 90.degree. between any adjoining tie bars in which to change dies on the faces of the platens or to remove castings after injection is completed and the dies open. The existence of four tie bars also limits the space available to adjust or remove core plates or ejector plates mounted behind the platens.
The tie bars used in existing machines are also relatively flexible flexing as much as 20 to 40 one-thousandths of an inch during clamping of the dies for injection. Extension of the tie bars of 20 to 40 one-thousandths of an inch or more can cause torsion forces in the frame of the die casting machine which may result in misalignment of the die faces during clamping if at least four tie bars are not used between the platens.
In prior art die casting machines it is known to use hydraulic open and close cylinders to bring the dies into proximity and to use a toggle arrangement or a second hydraulic mechanism to clamp the dies together immediately preceding and during injection. Said open and closing mechanism and said clamping mechanism are not disposed directly on the longitudinal centerline of the die casting machine and the application of such closing forces other than directly behind the dies can result in torsional forces in the frame of the die casting machine which may result in improper alignment of the dies during clamping and injection of the die casting liquid.
In prior art die casting machines the injection of metal into the dies is most frequently made through the sides of the dies. The liquid metal is stored in the melting pot normally above or below the side of the dies where the liquid metal is injected into the side of the dies. In travelling from the melting pot to the injection nozzle the injection fluid must turn through 90.degree. which results in turbulence in the casting liquid which can result in an inferior finish on the casting.
In order to reduce the time of the cooling cycle it is desirable to remove as much liquid metal as possible from the large inlet runner sections of the molds as soon as the metal in the gate solidifies. The positive withdrawal of molten liquid from the large inlet runner section is only marginally assisted by gravity when injection of metal into dies is made through the side of the dies.